Many runners tried barefoot running, but unfortunately many of they failed in succeeding it. This fact has been in controversies for may years among the people who prefer natural running. Why do many fail, and why do only some succeed? My answer is that technique for barefoot running totally depends on how your bodies are natural. If your bodies are far from ancient and original humans’ bodies, it is difficult of you to run with barefoot. Many runners and scientists have argued about techniques for barefoot running, and many of their opinions are not accepted among usual runners with shoes. To find a final answer, we have to descend to the times how we are born and how we grow up. The exercises during 0-year old are so important that the qualities of those exercises decide also the qualities of the motions after we grow up. Moreover, the qualities of baby exercises decide the nature of our bodies. If you have done high-quality of baby exercises during 0-year old, your body is surely natural, and barefoot running is so easy for you. My suggestion is that we do baby exercises again and make our bodies natural, and that we should follow a theory humans’ developments. Baby exercises come first, and barefoot walking and running follow it.